AllWords.com - http://www.allwords.com/
A dictionary of English language offering multi-lingual search. Also provides crossword solver, glossary and bookstore.
Canadian Directory of Special Collections - http://www.collectionscanada.gc.ca/collectionsp/index-e.html
Provides a list of places in Canada that house special collections and list some information on the material, including dictionaries, that is held in the various institutions.
Datasegment.com - http://onlinedictionary.datasegment.com/
Find definitions by alphabetical browsing or word lookup.
Definitions.net - http://www.definitions.net/
Browse thousands of dictionary definitions.
Pidic.com - http://www.pidic.com/
An online picture dictionary that is designed for children and young teens.
wordIQ - http://www.wordiq.com/
Allows users to search through many different dictionaries at the one time including some encylcopedia's as well.